As an avid gardener, you want to make sure that the soil is well protected in all weather conditions, and that it provides the nutrients your plants need to grow.
Organic mulch does exactly that. It creates a natural cover over your soil that protects the ground from hot sun, extreme wind and even unwelcome seeds that spread in spring and summer.
When you look around for the right organic mulch for your garden, you will find that there is a huge variety.
From colored wood, wood chips and straw to pine straw, shredded bark or seed hulls, you will need the right mulch to fit your garden.
In this ultimate guide to organic mulch, we explore the different types of natural mulch and how they benefit your soil.
What Is Inorganic Mulch?
Before we dive into the details for organic mulch, let’s first take a look at the opposite: inorganic mulch.
Inorganic mulch usually comprises of any non-plant material, such as gravel or rock. It can also contain landscape fabric, plastic sheeting or rubber mulch.
Inorganic mulch is designed to break down over a much longer period of time than organic mulch.
Although the inorganic type of mulch does cost a little more, it proves to be more cost-effective over time as it does not need to be reapplied as frequently as natural mulch.
However, one of the biggest disadvantages of inorganic mulch is that it does not add any nutrients to the soil because it doesn’t break down.
In addition, inorganic mulch may even prevent certain nutrients from entering the soil, which can have an impact on your soil quality.
While inorganic mulches, such as rocks or gravel, can add to the appearance of your garden, it may not be very beneficial for the soil.
Inorganic mulch can suppress the growth of weeds, but it doesn’t protect your garden plants from harsh cold or wind, and it doesn’t allow nutrients to enter the soil which can affect the growth of your plants.
Types Of Inorganic Mulch
Inorganic mulch can be a variety of things. Let’s take a look at the different types, and their benefits and disadvantages.
Gravel Or Rock
One type of organic mulch may be decorative rock or gravel. This can make your flower beds or larger landscape beds look very tidy and attractive.
You can apply ricks or gravel straight onto the soil or use a fabric/plastic sheet underneath. The sheeting will help suppress any growing weeds.
As stones take a long time to weather, you do not need to reapply them for a while.
The biggest disadvantage with gravel or rocks around your flower beds is that they absorb and reflect the heat from the sun.
And as rocks do not provide any nutrients and moisture to the soil, it can quickly dry out the ground. This means that you will need to be careful with the choice of plants.
The majority of plants do not like too dry and hot soil, so you will need to pick some drought resistant plants.
Alternatively, you can use decorative gravel or rocks only in areas where there are no plants growing.
Another disadvantage of this type of inorganic mulch is that it is costly and difficult to apply, and once it has been laid, it’s not easy to remove.
Plastic Sheeting
Plastic sheeting is one of the traditional mulch methods but it has proven to be damaging to the environment.
Some gardeners still like it because it effectively suppresses weeds. It also typically acts as a base for gravel or rock mulching making your garden look prettier.
However, although plastic sheet does save you money because it lasts longer, plastic sheeting does not allow any air, nutrients or water to get through to the soil.
This makes it impossible to use around any type of plants, in particular shrubs and trees that have a larger root system.
If you apply plastic sheeting around these plants, you will find that the plant or tree will slowly die over time.
Plastic sheeting also doesn’t allow the soil to breathe, which can have a serious impact on the insect and wildlife populations depending on soil.
With plastic sheeting effectively killing the soil where it is placed on, it is not a recommended mulching method.
Landscape Fabric
If you opt for a good quality landscape fabric, you can effectively suppress weeds growing in your soil.
The bonus with landscape fabric, compared to landscape sheeting, is that it allows water, air and nutrients to get down to the soil.
This is much more beneficial for the soil, plants and wildlife. In addition, you can also use landscape fabric as a base for other inorganic mulches or adding organic mulch.
However, it is essential that you use a high-quality landscaping fabric that does not break down or rip easily.
Rubber Mulch
Rubber mulch is typically made with tiny bits of recycled tires. The use of recycled materials is a great benefit.
It does suppress weeds very well and it also retains the moisture in the soil. Rubber mulch is often used for playgrounds because it keeps the ground soft and bouncy.
However, due to the chemical processes involved in making rubber, there may be toxic components in rubber mulch which can leak into the ground.
Additionally, rubber mulch doesn’t break down for a very, very long time, so it stays in the soil for much longer than some of the other inorganic materials.
What Is Organic Mulch?
Unlike inorganic mulch, organic mulch is any kind of mulch which contains dead plant material, including grass clippings, bark, leaves and even compost.
This type of mulch can break down tough soils and improve soil quality. As all the ingredients of organic mulch are natural, it does not contain any materials which your soil cannot break down.
The biggest difference between inorganic and organic mulches is that inorganic mulch does not decompose.
Benefits Of Organic Mulch
Natural or organic mulch has so many positive benefits for the soil and plants in your garden. Here are some of the biggest advantages of organic mulch.
Suppress Weeds
This is a general benefit of all mulches. They suppress weeds because they keep the soil underneath in the dark.
This means that any seeds of weeds will not be able to grow as they need a light source to germinate.
Unlike other mulches, organic mulch breaks the soil up and it keeps it lose, so that you can pull out any weeds that managed to find their way to the surface.
Add A Natural Finish To Your Garden
As organic mulch is applied on top of the soil, it can provide a naturally finished look to any empty spaces around trees or other plants.
Prevent And Reverses Soil Compaction
Soil that is too compact and thick doesn’t allow any roots or organisms to grow. Organic mulch can prevent this.
Thanks to small soil animals, such as pill bugs or earthworms, eating their way through the decaying mulch, they will create small air pockets inside the soil.
This will break up the soil, preventing and reversing any soil compaction.
Stop Topsoil From Eroding
Similar to the prevention of compact soil, organic mulches allows more air and water to penetrate the soil.
This means that any water from rain will not be washed away. In turn, this prevents the erosion of the topsoil layer.
Add Organic Material To The Soil
Organic mulch is made from natural, dead plant matter which means that it simply decays inside your soil.
This rotting process attracts tiny organism in the soil, and they will feed on this material and spread it across the soil taking it deeper into the ground.
Reduce Your Water Bill
Organic material always holds some moisture, even the dead plant material in your organic mulch.
Adding a thick layer of natural mulch will keep the soil watered for longer, which means that you can save on watering.
Additionally, the moisture in organic mulch is also released steadily to the soil. This will help plants to access water when they need it.
Keep Your Plants Clean
A good layer of organic mulch will significantly reduce any water splash-back on plants. A big plus with this is that it also reduces any soil-borne plant diseases.
Protect Soil From Temperature Changes
Over the year, temperatures can change a lot, and your plants are usually exposed to these temperature swings.
With organic mulch, you can create an insulation layer, which keeps the soil around the plant from drying out when it’s too hot.
Saying this, organic mulch is typically not the best option for cold climates as it will stop the soil from warming up.
This means that you should not apply organic mulch from later autumn to early spring.
If you live in an area where it does get very cold over winter, then you may want to consider using a plastic mulch.
Protect Trees From Lawnmowers
A very practical advantage of placing some organic mulch around your trees is that it will protect them from trimmers or lawnmowers.
The Best Organic Mulch: Recommended Types Of Organic Mulch
Time to take a look at the different types of organic mulch that we found work best in a variety of gardens.
We find out what they are best for, plus some of their advantages and disadvantages.
Wood Chip Mulch
Mulch with wood chips comes in a variety of different size chips. The smaller wood chips is known as ground wood mulch.
Mulch with smaller wood chips are ideal for mulching shrubs, trees, orchards, perennial flowers and flower beds, as well as walkways in a vegetable or flower garden.
The smaller the wood chips in the mulch, the better they will stay in place because larger wood chips can easily blow away with the wind and rain.
Depending on the wood chip size and how fine they are, you should apply a two to four inch thick layer of this organic mulch.
You can apply a thicker layer if your mulch has bigger wood chips.
As a rule of thumb, we recommend using only uncolored wood mulch, and avoid creating mulch volcanoes when mulching your trees.
You should also avoid applying wood chip mulch over any landscape fabric. Make sure that you apply this mulch only on the top of your soil.
This way, the wood mulch will not remove any nitrogen from the soil.
Advantages Of Wood Chip Mulch
One of the biggest advantages of wood chip mulch over some of the other organic mulches is that it does look attractive.
This mulch is ideal for adding organic matter to the soil. This can be particularly useful for perennial flowers.
Wood chip mulch allows water to penetrate the soil and it moderates the soil temperature very well.
This type of mulch doesn’t compact, and it can even reverse soil compaction.
Disadvantages Of Wood Chip Mulch
You will need to ensure that you buy the smaller wood chip sizes, so to avoid any of the mulch being blown away.
A general disadvantage of mulch is that it does need topping up, so you will need to add wood chip mulch with smaller chips every one to two years.
Wood chip mulch with larger chips will need topping up every one to three years.
Straw Mulch
While wood chip mulch isn’t ideal for vegetable patches, straw mulch is perfect for your vegetable garden.
It keeps the soil cool during the warm summer months. However, you will need to use plastic mulches during the cooler winter months for protecting your vegetables from frost. You should apply between two and three inches of straw mulch on top of the soil to get the most out of your mulch.
When you are looking for straw mulch, make sure that you do not buy hay. Hay will have a lot of weed seeds in which you do not want in your veg patch.
We also recommend watering your straw mulch a few weeks before you apply it. This way, any weed seeds that may have been caught in the straw will sprout and you can pick them out easily.
Advantages Of Straw Mulch
Just like other organic mulches, straw mulch adds organic material to your soil and it suppresses weed growth.
It also releases water into your soil slowly, keeping the moisture levels in your soil well balanced.
Straw mulch can also be turned under at the end of every season.
Disadvantages Of Straw Mulch
As it is very light when you spread it out, straw mulch can easily blow around.
If you are not careful when buying straw mulch, you may end up with a lot of weeds in your mulch that need picking out.
Corn Stalks And Corn Cobs
Corn cobs are not just a delicious vegetable, but you can also use corn cobs and corn stalks as mulch for vegetables patches in your garden.
If you want to use corn cobs and corn stalks as mulch, then you need to make sure that they are shredded and ground properly.
It’s also best to mix them with straws in order to avoid any matting which could lead to soil compaction.
You can apply the mulch mix at a depth of around 2 inches.
Advantages Of Corn Mulch
Corn stalk mulch is ideal as a winter mulch for your vegetable garden. It allows water to penetrate the soil and it regulates the soil temperatures.
As it is free of any weed seeds, you can also easily turn it in spring.
Disadvantages Of Corn Mulch
Similar to straw mulch, corn stalks tend to blow away, and they can also mat if not mixed with straw.
Another disadvantage of shredded corn stalk mulch is that it doesn’t look very appealing in your garden.
Cotton Burrs
Cotton burrs are one of the best mulches for vegetable gardens. However, you will need to make sure that your cotton burrs come from a farmer who does not use any chemically defoliated plants or pesticides.
Advantages Of Cotton Burrs Mulch
As an organic material, cotton burrs suppresses any weed growth and it allows water to trickle down to the soil.
Disadvantages Of Cotton Burrs Mulch
You will need to be very careful where you source your cotton burrs from. You shouldn’t use any cotton burrs with chemically defoliated plants.
Evergreen Boughs
You can also use evergreen branches as a mulch. This is best suited for small shrubs and perennial plants which need some protection over the cold winter months.
Apply several layers of the branches before the first frost, and remove the mulch in late spring.
Advantages Of Evergreen Boughs Mulch
Evergreen boughs provided excellent insulation for your perennials and shrubs over the winter.
Disadvantages Of Evergreen Boughs Mulch
There are no real disadvantages to this type of natural mulch. Just make sure that you apply enough layers.
Green Manure/Cover Crops
Green manure and cover crops can be an ideal organic mulch to reduce any weed growth in your orchard and vegetable patches.
You can use winter rye, buckwheat, ryegrass or barley for this purpose. It’s important that you either cut them down or turn them before they start to seed.
Otherwise, these grasses will spread quickly.
Advantages Of Cover Crops
Cover crops allow water to enter the soil and it helps to prevent the water from evaporating again.
And added benefit with cover crops is that they also attract a range of different insects when they start to flower.
Disadvantages Of Cover Crops
The biggest advantages of growing a cover crop as mulch is that you will not be able to grow vegetables at the same time.
Lawn Clippings Mulch
Lawn clippings as a mulch is ideal for mulching your lawn. With this, you will need a mulching mower but the investment is worth it because you will be able to reduce your lawn fertilizer by around 25%.
Apply up to one inch of lawn clippings on your lawn. It’s important that you do not use any lawn clippings that have been sprayed with weed killer or that are in seed.
Advantages Of Lawn Clippings
Lawn clippings add plenty of organic material to your lawn, and it can be turned at the end of the season.
Disadvantages Of Lawn Clippings
Unfortunately, lawn clippings can easily blow away (especially when dry), and it can quickly turn into a slimy mess (when raining).
It’s best to allow the clippings to dry first and then apply them in a thin layer.
Leaf Mulch
Shredded leaves used as leaf mulch are ideal for ornamental gardens and vegetable gardens.
Mix the shredded leaves with some straw and all it in a layer of two inches thick.
Advantages Of Leaf Mulch
Leaf mulch adds so much natural matter to the soil. Together with all the other positive benefits of organic mulches, leaf mulch’s biggest advantage is that it is free.
Disadvantages Of Leaf Mulch
You will need to combine the shredded leaves with straw or it will blow away.
Another disadvantage of leaf mulch is that you will need to collect the leaves in autumn, and then store them dryly over the winter to apply them in spring.
Living Mulch
When you use perennial groundcovers, such as thyme or veronica, as a mulch, then this is called living mulch. It is ideal for orchards and ornamental gardens.
Advantages Of Living Mulch
When you use veronica or thyme as a living mulch, then this can look very attractive in your garden.
Living mulch suppresses wood growth and it moderates soil temperature. Plus, it does not wash or blow away.
Disadvantages Of Living Mulch
As living mulch is indeed alive, it can take over some of your garden and you will need to prune it regularly.
Nutshells (Ground Or Cracked)
You can also cracked or ground nutshells, such as peanuts, hazelnuts or pecans, as mulch for ornamental gardens. Apply a minimum of two to three inches.
Advantages Of Nutshell Mulch
Mulch made of nutshells allows water to penetrate the soil and it keeps weeds at bay. Depending on your chosen nutshells, they can be reasonably slow to decompose.
Disadvantages Of Nutshell Mulch
Unless you have a way to crack or grind the nuts, nutshell mulch is very expensive. In addition, cracked nutshells can have sharp edges.
Pine Straw
Pine straw made of pine needles can be used for orchards and ornamental gardens. This type of mulch is also suitable for vegetable patches.
Just add a three inches thick layer of pine needles on top of the soil. This will not affect nitrogen and pH levels in your soil.
Advantages Of Pine Straw Mulch
Pine straw allows water to drip through to the soil, and it controls the soil’s temperature.
Pine needles last a relatively long time, and it prevents any weed growth. Similar to pine needs around the base of a tree, pine straw helps protect plants during the cold winter months.
Disadvantages Of Pine Straw Mulch
The biggest disadvantage with pine straw is that it cannot be turned under at the end of the season.
In addition, it can be a fire hazard in summer when it is very dry, and it does not suppress weed as well as some other organic mulches.
Seed Hull Mulch
Seed hulls from buckwheat, rice, cotton or coca beans can be used for mulching in vegetable gardens.
Just add a layer of up to 2 inches of seed hulls.
Advantages Of Seed Hull Mulch
Seed hull mulch does look very attractive in and around the garden. It has the same benefits as many other organic mulches, with the added benefit that it can be turned under at the end of the season.
Disadvantages Of Seed Hull Mulch
As seed hulls are very light, they can easily get blown around the garden.
In addition, you need to make sure that the seeds and plants have not been sprayed with pesticides. This is particularly true for cotton.
All seed hulls need to be replenished after one year, and you will need to be careful with overwatering as some seed hulls, such as cocoa, tend to get moldy if they are too damp.
Newspaper And Cardboard
Cardboard and newspaper is a quick and easy mulching solution when you are looking to suppress weeds.
Just wet a few sheets newspaper/cardboard and add them on top of the soil. You need to make sure that you overlap the edges.
You can then cover the cardboard or newspaper with up to three inches of wood chips or straw.
It’s important that the cardboard and newspaper aren’t drying out as this could damage the soil underneath.
Coffee Grounds
Coffee grounds need to be combined with other mulch options to be effective. They are best used in vegetable and ornamental gardens.
In order to use coffee grounds as an effective mulch, you will need to apply around half an inch of coffee grounds onto the soil, and then cover it with maximum four inches of a coarse organic mulch, such as straw or wood chip.
It’s important that you do not apply coffee grounds anywhere near seeds because it will affect the germination rates of the seeds.
Coffee grounds should be treated similar to compost, and this is where they are typically used.
Advantages Of Coffee Ground Mulch
Coffee grounds add organic material to the soil and they allow water to penetrate the soil.
You can easily turn it at the end of the season if you choose to cover it with another organic mulch that can be turned at the end of the season.
Disadvantages Of Coffee Ground Mulch
Coffee grounds can build a compact, thick layer over time, if they aren’t covered with another mulch.
Compost
Compost is a popular mulch across many gardens. However, you should not use them in native and rock gardens where the soil should be lean.
Before you apply compost, it is important that you do an accurate soil test. This will indicate whether you need to add compost to your soil.
We recommend using compost in a similar way to coffee grounds. Just add it as a base layer around two inches thick, and then apply a second layer of mulch, such as straw or shredded leaves, on top.
Advantages Of Compost Mulch
Compost is a great way to add organic matter to your soil. It is typically free, when commercially produced.
Disadvantages Of Compost Mulch
The greatest disadvantage of compost used as a mulch is that you do need to cover it up with another mulch, otherwise the weeds will germinate wildly.
It should be applied in layers of up to three inches thick.
Advantages Of Shredded Wood Mulch
Shredded wood controls the temperature of your soil effectively, and it adds organic material to the soil.
Bark mulch should be free of weed seeds. Then it can last a longer period of time than some other mulches.
Disadvantages Of Shredded Wood Mulch
Shredded wood mulches can compact after some time, and then build a barrier against water penetration.
Another disadvantage of bark chip mulch is that it is expensive, compared to wood chip mulch.
Types Of Organic Mulch That Are Not Recommended
Now that we have seen some of the best types of organic mulch, let’s take a look at mulches that aren’t suitable for most gardens.
Peat Moss
In some gardens, you will find that peat moss is a great option for soil amendment, but it is not the right choice as a mulch.
Peat moss blows away easily. When peat moss is wet, it can crust over the soil, drying it out. On the other hand, when peat moss is dry, then it will extract water from the soil, making it even drier.
In addition, due to the way in which it is harvested, peat moss is not a sustainable solution.
Salt Marsh Hay
Typically available in the North East of the US, salt marsh hay is taken from sensitive coastal and flood plain areas.
This causes serious damage to the plants and wildlife in these parts of the world, so it is definitely not an environmentally sustainable mulch.
Sawdust And Wood Shavings
Wood shavings and sawdust belongs into your compost where it is much more useful.
As a mulch, it crusts over and can block any water from penetrating through the soil. This can damage the soil after a while.
In addition, it also ties up any nitrogen in the soil, if you turn it over at the end of the season.
Conclusion
Finding the right organically grown mulch for your garden does not have to be difficult.
Generally, it is important to look out for certified products, and you need to ensure that no herbicides or pesticides have been used.
The best mulch is usually tree-based, so these would be pine needles and chipped wood. This does not have to be expensive, especially when you can use any of the organic material in your own garden.
